There are known several different principles of operating a gas injection valve, one of this is based on the venturi principles, for instance described in WO 2004/092537 A1. Another approach is to have a central stem with outer sealing surface and through going flow between an outer housing and the central stem across the sealing surfaces, for instance described in CA 02461485 A1.
After a period of time, known gas lift valves will have a tendency of not working as expected. One problem might be the erosion of the sealing surfaces of the valve device which lead to leakage across the valve seat and reduced performance and a reduced lifetime for the valve devices. This creates a problem for operation of the well with increased down time, maintenance time and an increased safety hazard.
An aim with the present invention is to minimize and possibly alleviate these problems. It is also an aim to provide a device with a true metal to metal sealing of the device. Metal to metal seal in a preferred embodiment is understood to be a single seal between two metallic surfaces without any secondary seal, soft seal or a combination of such. It is also an aim to provide a device with a reduced erosion rate of the sealing surface. Another aim is to provide a device with an increased flow area compared with similar known valves. There is a further aim to provide a device with minimal flow restrictions and disturbances in the injection flow, giving reduced pressure losses across the device.